Added missing active record configurations.

guides/source/configuring.md

@@ -273,6 +273,12 @@ config.middleware.delete "Rack::MethodOverride"
 
 * `config.active_record.cache_timestamp_format` controls the format of the timestamp value in the cache key. Default is `:number`.
 
+* `config.active_record.record_timestamps` is a boolean value which controls whether or not timestamping of `create` and `update` operations on a model occur. The default value is `true`.
+
+* `config.active_record.partial_writes` is a boolean value and controls whether or not partial writes are used (i.e. whether updates only set attributes that are dirty). Note that when using partial writes, you should also use optimistic locking `config.active_record.lock_optimistically` since concurrent updates may write attributes based on a possibly stale read state. The default value is `true`.
+
+* `config.active_record.attribute_types_cached_by_default` sets the attribute types that `ActiveRecord::AttributeMethods` will cache by default on reads. The default is `[:datetime, :timestamp, :time, :date]`.
+
 The MySQL adapter adds one additional configuration option:
 
 * `ActiveRecord::ConnectionAdapters::MysqlAdapter.emulate_booleans` controls whether Active Record will consider all `tinyint(1)` columns in a MySQL database to be booleans and is true by default.